Remove libjsoncpp dependency

The libjsoncpp is not directly used by dnsresolver.

Test: adb shell dumpsys netd.
      The resolver binder call is still being printed.

Bug: 151122313
Merged-In: Ib9acab126ae0a9e25312d871bd1160f68947d2f8
Change-Id: I22ff86300114a0981fb6a4b8c0202bddae78f5ac
(cherry picked from commit 96fa8287)